Adjustable discharge nozzle for jet engines



Aprll 2 1953 J. J. AMBROSE ET AL 2,635,419

ADJUSTABLE DISCHARGE NOZZLE FOR JET ENGINES I Filed Sept. 50, 1948 3 Sheets-Sheet 1 INVENTORE ,JDHN J. AMBROSE. 'JEISEF'H MDDRDVEKY.

ATTORNEY ADJUSTABLE DISCHARGE NOZZLE FOR JET ENGINES 3 Sheets-Sheet 2 Filed Sept. 30, 1948 ENT MIJD

ATTORNEY A nl 21, 1953 J. J. AMBROSE ETAL 2,635,419

' ADJUSTABLE DISCHARGE NOZZLE FOR JET ENGINES Filed Sept. 50, 1948 5 Sheets-Sheet 5 w L 56 LL INVENTOREI N .J. AMBROSE. .m' gpu MEIDRDVEKY.

ATTORNEY Patented Apr. 21, 1953 ADJUSTABLE DISCHARGE NOZZLE FOR JET ENGINES John J. Ambrose, Packanack Lake, and Joseph Modrovsky, River Edge, N. J., assignors to Curtiss-Wright Corporation,

Delaware a corporation of Application September 30, 1948, Serial No. 51,914

2 Claims.

This invention relates to jet engines and is particularly directed to an adjustable discharge nozzle construction for such engines.

The invention is applicable to all types of engines having a duct through which gases discharge for providing at least a portion of the forward propulsive thrust of the engine. As is well known, the efiiciency and propulsive thrust obtained with such engines may be controlled by providing adjustable nozzle means for varying the area of the discharge opening of the exhaust duct. This feature is particularly important for eflicient operation of jet engines on aircraft. In the prior art, such a nozzle generally comprised a body disposed within and movable longitudinally of the exhaust duct for varying its discharge area. This conventional construction is objectionable because the moving parts of the nozzle are disposed within the exhaust duct and therefore are subjected to the high temperatures of the exhaust gases discharging through said duct. An object of this invention comprises the provision of a novel adjustable exhaust nozzle construction for jet engines in which the moving parts of said nozzle can all be disposed externally of the exhaust duct.

Specifically, the discharge nozzle of the present invention comprises a construction simulating a clam-shell in which each half of said clamshell-like nozzle comprises a member which is mounted adjacent the discharge end of said duct for pivotal movement toward and away from the other of said members across at least a portion of the discharge opening of said duct. Each of said nozzle members is pivotally mounted on bearings or trunnions disposed externally of and ondiametrically opposite sides of the exhaust duct. In addition, each of said nozzle members preferably comprises a spherical segment having a spherical inner surface corresponding to the spherical surface portion of a spherical wedge. Also provided are means for shielding said nozzle bearings from the heat of the exhaust duct and means for providing a seal between the end of said exhaust duct and said spherical nozzle segments.

Other objects of the invention will become apparent upon reading the annexed detailed description in connection with the drawing in which:

Figure 1 is a plan view of an exhaust duct having an adjustable nozzle embodying. the invention, this view being taken along line ll of Figure 3;

Figure 2 is a sectional view taken along line 22 of Figure 3 with a portion of the duct broken away;

Figure 3 is a sectional view taken along line 33 of Figure 1;

Figure 4 is a view taken along line 4-4 of Figure 3; and

Figure 5 is a sectional View taken along line 55 of Figure 4.

Referring to the drawing, reference numeral Ill designates the discharge end of the tail pipe or exhaust duct of an engine, the engine exhaust gases discharging through said duct for providing said engine with forward propulsive thrust. As illustrated, the discharge end of the duct H) has a generally circular cross-section. A pair of co-axial stub shafts or trunnions 12 are supported externally of and on diametrically opposite sides of the duct l0 adjacent to the discharge end of said duct. Each trunnion i2 is supported at its inboard end by a bracket construction l4 mounted directly on the duct It as illustrated, and is supported at its outboard end by a bracket construction is secured to the duct 10 by means not shown.

A pair of spherical sheet metal segments l8 and 20 are mounted for pivotal movement across the discharge end of the duct E0 to comprise a Variable nozzle for said discharge end. Each said spherical segment [8 and 28 has a spherical inner surface correspondin to the spherical surface of a spherical wedge in which the planes forming the sides of said wedge intersect along the axis of the trunnions l2. Re-enforcing channel shaped stiffener members 22 are secured along the two edges of each spherical nozzle segment I8 and 20. A pair of bearings 24 are supported by each trunnion l2, one for each of the spherical nozzle segments l8 and 2&3. Each spherical segment i8 and 2G is pivotally mounted on the trunnions [2 by said bearings. For this purpose, the two ends of the spherical segment I8 are secured to hubs 26 and 28 respectively, each of said hubs being journaled on a bearing 24 and each of said ends having a semi-circular cut-out portion extending approximately half way around its associated hub. The two ends of the spherical segment 20 are similarly formed and secured to hubs 3t and 32 which are journaled on bearings 24.

The spherical nozzle segments l8 and 20 extend about diametrically opposite sides of the axis of the duct 10 in such a manner that each said segment is pivotally movable, about the axis of the trunnions it, over the adjacent end of said duct and toward the other of said segments to vary the discharge area of said duct. Each of the segments I8 and 20 subtends an angle of approximately 180 about the axis of the duct III. In order that the spherical nozzle segments I8 and 28 are always symmetrically positioned relative to the axis of the duct III, they are connected together for equal simultaneous movements. For this purpose, the two ends of the segment I8 are provided with cylindrical tracks 34 and 38 respectively. Similarly the two ends of the segment 20 are provided with cylindrical tracks 38 and 48 respectively. The cylindrical tracks 34, 38, 38, and 40 are all co-axial with the axis of the shafts I2. In addition, the tracks 34 and 38 of the segments I8 and 20 respectively are disposed adjacent to each other on one side of the duct III while the tracks 38 and 40 of the segments I8 and 28 respectively are disposed on the other side of said duct. Flexible steel bands 42 and 44 are connected at one of their ends to the tracks 34 and 38 respectively and at their other ends said bands are connected to opposite ends of a semi-cylindrical drum 48. Flexible steel bands 48 and 50 are similarly connected to tracks 38 and 40 respectively and to the opposite ends of a semi-cylindrical drum 52 co-axial with the drum 48.

The tracks 34, 38, 38, and 40 and the drums 48 and 52 all have the same radius. The arrangement is such that said flexible bands are placed under tension and the tension in the bands 42 and 44 rotatively urge their respective segments in a counter-clockwise direction while the tension in the bands 48 and 50 rotatively urge their respective segments in a clockwise direction. With this construction, the flexible bands 42, 44, 48, and 58 and associated tracks and drums form a light-weight connection between the spherical nozzle segments I8 and 28 whereby said segments are secured together, with no backlash or play, in such a manner that any pivotal movement of one segment is accompanied by an equal and opposite pivotal movement of the other segment.

Suitable piston and cylinder fluid motors 54 are mounted on the external surface of the duct II) for pivotally swinging the segments I8 and 28 about the axis of the trunnions I2. The motors 54 may obviously be controlled from a remote point by any suitable valving arrangement. In their full line position, as illustrated in Figure 1 of the drawing, the spherical nozzle segments are fully open whereby the forward propulsive thrust obtained from the jet is a minimum. The magnitude of said thrust may be increased by decreasing the discharge area of the nozzle by swinging the spherical nozzle segments I8 and 20 toward each other, for example to their positions illustrated in Figure 1 of the drawing by dashed lines I81: and 20a.

A seal construction 58 is supported on and about the discharge end of the duct I in engagement with the inner spherical surfaces of the segments I8 and 20 to prevent discharge of the engine exhaust gases forwardly between the spherical nozzle segments I8 and 20 and the exhaust duct I8. Any such reverse flow of the exhaust gases would reduce the thrust obtained from the jet engine. As illustrated, said seal construction comprises a pair of semi-circular bands 51 and 58 for the spherical segment I8 and a pair of similar semi-circular bands 59 and 80 for the spherical segment 28. The band 58 embraces the band 51 and said band 58 has one edge slotted, as indicated at 8I, to provide a plurality of fingers resiliently engaging the inner surface of the spherical segment I8 to prevent flow of gases between said band and segment. The band 81 is also slotted and the fingers formed thereby are disposed so as to underlie the slots in the band 58 to prevent leakage therethrough. The bands 51 and 58 are supported on the duct I8 adjacent to its discharge end by a semi-circular bracket 82 which also serves to prevent flow of the exhaust gases between said bands and duct. The flexible bands 59 and 88 have a construction similar to that of the bands 51 and 58 and are similarly supported from and adjacent to the discharge end of the duct II).

The sides of the duct I0 between the spherical nozzle segments I8 and 20 are preferably extended rearwardly beyond the seal 58, as indicated at 83, to help prevent the exhaust gases from discharging laterally between the spherical nozzle segments I8 and 20. The duct extensions 83 are curved inwardly, as illustrated in Figures 3 and 5, so as not to interfere with swinging movements of the spherical nozzle segments I8 and 20. Except for the extensions 83, the exhaust end of the duct I0 is circular as illustrated in the drawing.

The spherical nozzle segments I8 and 20 may be moved toward each other beyond their dotted line positions of Figure 1 so that their adjacent edges at least substantially abut on the axis of said duct whereupon the other edge of each spherical nozzle segment is disposed beyond its respective seal band thereby leaving a gap between each spherical nozzle segment and its seal band. With the spherical nozzle segments so disposed, the exhaust gases will be deflected by said segments through said gaps at right angles to the axis of said duct. In the case of an aircraft jet engine, such a lateral discharge of the exhaust gases will eliminate the forward thrust of the jet engine and will provide the aircraft with substantial drag whereby jet powered aircraft can be landed at reduced speed. Also, with the spherical nozzle segments I8 and 20 at least substantially abutting to eliminate the forward thrust of the jet engine, said engine may be operated at normal full power conditions but with substantially no forward thrust whereby full forward thrust may be obtained merely by moving the spherical segments I8 and 20 apart to positions in which they overlie their respective seal bands.

As illustrated, one end of each spherical segment I8 and 20 is mounted on an inboard bearing 24 while its diametrically opposed end is mounted on an outboard bearing 24. With this construction, the segments I8 and 20 can be made alike. However, if the spherical nozzle segments are to be constructed so that they may be pivotally moved to a position in which they overlap on the axis of the duct I0, then the one segment must be larger than the other and the ends of the larger segment should be pivotally mounted on both outboard bearings 24 while the ends of the smaller segment should be pivotally mounted on both inboard bearings 24.

In order to shield the bearings 24 from the heat of the engine exhaust gases in the duct III, a substantially fiat shield 84 is disposed between each pair of bearings 24 and the adjacent wall of the duct I0. Each shield 84 divides a housing portion of its associated bracket construction [4 into a pair of chambers 88 and 88. In addition, a pair of conduits I0 are mounted externally of the duct I8 on opposite sides thereof adjacent the trunnions I2. One end of each duct I0 communicates with the chambers 66 and 88 of its associated bracket l4 and its other end terminates adjacent to the discharge end of the duct [6. Openings [2 communicate with the forward ends of the chambers 66 and 68. With this construction, the exhaust gases discharging from the exhaust l induce air flow through the openings 72, chambers 66 and 68 and the passageways provided by the conduits I0. In this way, during engine operation a cooling air flow is maintained o er both sides of the shield 64 thereby keeping said shields cool to minimize radiation of heat to the bearings I2.

As described, the duct ID has a circular crosssection and the nozzle segments l8 and 20 have spherical inner surfaces. This spherical nozzle construction is preferable because it provides maximum strength with minimum weight since said spherical segments are loaded in pure tension by the gas pressure acting thereon. In addition, with the spherical construction of the nozzle segments, the gas loads acting on said segments are balanced relative to their pivot axis so that only small control forces are required for moving said segments. Obviously, however, the duct [0 may have a cross-section other than a circular cross-section. Regardless of the crosssectional shape of the duct !0, the nozzle segments may still be spherical as illustrated, since it is only necessary to modify the inner periphery of the brackets 62 of the seal 56 to fit that of the duct I0 while its semi-circular bands 58 and 69 contact the nozzle segments. If desired, however, even where the cross-section of the duct 19 is other than circular, the profile of each nozzle segment, in a plane including the pivot axis, may be formed parallel to the profile of said duct in said plane, while the profiles of said segment in planes perpendicular to its pivot axis are circular about said axis.

While we have described our invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding our invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. We aim in the appended claims to cover all such modifications.

We claim as our invention:

1. A variable discharge nozzle for an engine having an exhaust duct with a discharge opening through which gases discharge for providing said engine with forward propulsive thrust; said nozzle comprising a pair of movable members disposed on opposite sides of said duct; trunnion means disposed externally of said duct for pivotally mounting each of said members about an axis directed across said duct adjacent to its discharge end so that said members can be pivotally moved toward and away from each other over the discharge end of said duct to vary its discharge area, said trunnion means including a pair of bearing assemblies supported by and disposed on opposite sides of said duct; a pair of shields, one for each of said bearing assemblies, each said shield being disposed between its associated bearing assembly and the adjacent external portion of said duct and being spaced from said duct and its adjacent bearing assembly; a pair of means, one for and disposed about each of said shields to form a pair of first and second passageways disposed along opposite sides of the associated shield, one of said passageways of each pair being disposed between its associated shield and said duct and the other passageway of said pair being disposed between. its 8 9 ated shield and the adjacent bearing assembly with each of said passageways having one end communicating with the surrounding atmosphere; and means providing a pair of third passageways, one for each of said shields and extending from the other ends of the associated first and second passageways into the fiow path of the gases discharging from said duct so that gas flow through said duct helps to cause a fiow of air through said passageways over both sides of the associated shield for cooling said shields.

2. A variable discharge nozzle for an engine having an exhaust duct through which gases discharge for providing said engine with forward propulsive thrust; said nozzle comprising a pair of pivotally movable members, each of said members having its ends pivotally connected to said duct at diametrically opposite sides of said duct adjacent to the discharge end of said duct and extending approximately half way about the axis of said duct so as to be pivotally movable over the edge of and across at least a portion of the discharge end of said duct to vary the discharge area of said duct; and means connecting said members for restraining said members to equal but opposite rotative movements; said connecting means including a pair of cylindrical drums pivotally mounted adjacent to said opposite duct sides with the pivot axis of each drum disposed parallel to the pivot axis of said members; a first pair of cylindrical tracks, one for and secured to each of said members adjacent to one of said cylindrical drums; a second pair of cylindrical tracks, one for and secured to each of said members adjacent to the other of said cylindrical drums; a first pair of tensioned flexible bands each having one end connected to one of said cylindrical drums and its other end connected to one of the adjacent cylindrical tracks such that the tension in said bands urges said members in the same rotative direction and the tension in one band urges said drum in a direction opposing the tension in the other band; and a second pair of tensioned flexible bands each having one end connected to the other of said cylindrical drums and having its other end connected to one of the adjacent cylindrical tracks such that the tension in one of said second bands urges said other drum in a direction opposing the tension in the other of said second bands and the tension in said second pair of bands opposes rotative movement of said mem bers by the tension in said first pair of bands.

JOHN J. AMBROSE.

JOSEPH MODROVSKY.

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